Hermann Joseph Muller quotes:

The central problem of biological evolution is the nature of mutation, but hitherto the occurrence of this has been wholly refractory and impossible to influence by artificial means, although a control of it might obviously place the process of evolution in our hands.

Natural selection based on the differential multiplication of variant types cannot exist before there is material capable of replicating itself and its own variations, that is, before the origination of specifically genetic material or gene-material.

As science is more and more subject to grave misuse as well as to use for human benefit it has also become the scientist's responsibility to become aware of the social relations and applications of his subject, and to exert his influence in such a direction as will result in the best applications of the findings in his own and related fields. Thus he must help in educating the public, in the broad sense, and this means first educating himself, not only in science but in regard to the great issues confronting mankind today.

The gene as the basis of life.

There is no permanent status quo in nature; all is the process of adjustment and readjustment, or else eventual failure. But man is the first being yet evolved on earth which has the power to note this changefulness, and, if he will, to turn it to his own advantage, to work out genetic methods, eugenic ideas, yes, to invent new characteristics, organs, and biological systems that will work out to further the interests, the happiness, the glory of the God-like being whose meager foreshadowings we the present ailing creatures are.

To say that a man is made up of certain chemical elements is a satisfactory description only for those who intend to use him as a fertilizer.